The Giant Binocular

[woodchucker]

doooh.. you passed the spot. oh .. can you fix it?

 

[twhite]

Can you adjust for more side to side overhang with the tool on your machine? Or how do you correct it with a machine? I know that’s how I did it grinding by hand.


Cutting oil is my blood.

 

[savarin]

yes, more over lap, not a problem.

 

[savarin]

I thought a sharpie test would be worth a shot.

A quick ten mins to produce this

Still grinding in the centre and also a hint at the very edge.
I think another 1/8" overlap is worth a try

 

[savarin]

I ended up with 42mm overlap and reached the desired reading of 0.0179 on the spherometer with no zones indicated.
Now to get the lap to the neutral position where it doesnt alter the depth of the curve in either direction.
I started with a sharpie pattern again and started at 15mm overlap (had to start somewhere)

The first go showed it deepening the curve so I moved it out a bit and tried again.
Eventually I reached 22mm overlap where the sharpie marks all appear to wear at the same rate and the spherometer reading didnt change or show any zones.

Its probably not exact but the next grit should be very very close.

 

[Downunder Bob]

Charles your perseverence is amazing.

 

[savarin]

Ha ha Bob, I'm unsure if its perseverance or flogging a dead horse.
I must admit I'm feeling a bit more positive now.

 

[savarin]

not much done of late, life got in the way.
finished 600 grit and starting 800 asap.

the tiles were wearing down to the point where I decided to add now ones on top with a dab of silicone.
I didnt want them so thin by the time I get to 1500 grit.

I left the gaps between the tiles empty as this has reduced the suction making it easier to lift off the mirror.

Hmm, looks like I missed a bit in the clean up of the 600 grit, I better scrub this bit clean before I contaminate the 800 grit

 

[Eyerelief]

the tiles were wearing down to the point where I decided to add now ones on top with a dab of silicone.
I didnt want them so thin by the time I get to 1500 grit.

An amazing process! Cool beyond words!!

 

[savarin]

I blame the weather, it was just over 100'F in the shed.
I was going to post the next set of grits just to show I was still working over the holidays.
I took 3 hours to ensure I was at the neutral position with the new grit.
I wondered why I couldnt see any difference in the surface smoothness with the new 800 grit.
except it wasnt 800, it was 600 grit still.
DOH!